This invention relates to preshaped tubular catheters for percutaneous transradial approach to catheterization.
Preshaped catheters are commonly used for medical procedures such as diagnosis or such as coronary angioplasty or coronary stent implantation in which they serve to guide other catheters such as pressure measuring or balloon or stent loaded balloon catheters. In these procedures, a femoral approach is currently used in which the preshaped catheter is introduced into the aorta via the femoral artery, and the catheter is then manipulated at its proximal end, by push or pull and/or torque motions, for steering its distal end into the lumen of the selected vessel. To assist in advancing the catheter through the cardiovascular system, a relatively stiff guidewire is inserted into the catheter to straighten it out and bring the tip of the catheter in the direction of origin of the selected artery prior to actual cannulation. After the catheter is inserted into the artery, the guidewire is withdrawn, and the catheter may serve for a diagnosis procedure or for the guidance of another catheter such as a balloon catheter or a stent loaded balloon catheter.
In order to properly achieve its guiding function, the preshaped catheter should have an efficient backup or stability in the region where it is placed in order to withstand the efforts and motions of the pulsating environment as well as the stresses and deformations caused by the passage of the balloon catheter or other catheter or other equipment which it guides. It should also assure a good coaxiality for proper alignment with the ostium of the artery to avoid loss of push force on the guided catheter or the risk of trauma caused by a stent loaded balloon catheter entering the vessel in a misaligned condition. Furthermore, the preshaped guiding catheter should have some automatic configurational adaptability to easily find its way through the vascular system with a minimal amount of manipulations to whenever possible reduce the load of positioning travels for the patient. It should also have an appreciable capacity to deal with a variety of take-offs or angular positions which the left coronary artery, the right coronary artery or venous by-pass grafts may have with respect to the aortic arch. And when in the selected position, the catheter should lock in place and be releasable only under longitudinal tension from the operator.
Accordingly, the preshaped guiding catheters should have a configuration of lines, curves and/or angles which precisely match the environmental context in which they will have to be used and it is therefore practically impossible to simply foresee the effects of changes made to the catheter shape.
A great number of preshaped catheters have been designed over the years for the transfemoral catheterization.
For instance, the most commonly used catheter for left coronary arteries, namely the catheter referred to as the "left Judkins" which comprises an elongated straight shaft portion followed by a distal end portion consisting of a straight portion extending from the shaft portion and followed by a curved portion for approximately 180.degree. followed by a straight portion forming a small angle with the straight portion extending from the shaft portion, this last straight portion terminating in a tip portion substantially perpendicular thereto. This catheter is often made of a plastic material, and most of the catheters of that kind have a flexibility which is unmodulated along their length. They are also supplied in canted configurations to meet particular take-off requirements. This kind of catheter cannot be applied to right coronary arteries and, therefore, another catheter has been designed for right coronary arteries, namely the catheter referred to as the "right Judkins", also made of a plastic material, which comprises an elongated shaft portion having the shape of an elongated S terminating in a tip portion substantially perpendicular to the distal end of the S shaped shaft portion. Most of the catheters of that kind also have a flexibility which is unmodulated along their length.
Other preshaped catheters made of a plastic material, most of which have a flexibility which is unmodulated along their length have been designed, for example the catheters described in the document WO 92/12 754 the purpose of which is to improve over the "Judkins" catheters. According to a first embodiment, intended for left coronary arteries, the catheter comprises a first straight shaft portion followed by a distal end portion comprising a second straight portion extending at an angle to the first straight portion, followed by a curved portion for approximately 180.degree. followed by a third straight portion substantially parallel to the second straight portion, and a tip portion extending from and at an angle from the third straight portion, this tip portion extending behind the first straight shaft portion; this catheter is adapted for use with a relatively stiff wire inserted therein. A second embodiment, also intended for left coronary arteries and for use with a stiff wire inserted therein comprises an elongated first straight shaft portion followed by a distal end portion consisting of a second straight portion extending at an angle to the first straight shaft portion, a curved portion extending from the second straight portion for approximately 180.degree., a third straight portion extending from the curved portion at an angle to the second straight portion, and a tip portion extending at an angle to the third straight portion and parallel to the second straight portion, the tip portion extending behind the first straight portion. A third embodiment, also intended for left coronary arteries and use with a stiff guiding wire, and more particularly for left coronary arteries which are angularly displaced posteriorly from their normal distance (a situation referred to as posterior take-off), comprises a first straight portion extending from the proximal end of the catheter, and a distal end portion consisting of a second straight portion extending at an angle to the first straight portion and followed by a curved portion extending for approximately 180.degree., the curved portion being followed by a third portion terminating in a tip portion; in this catheter, the first and third straight portions are bent out of the plane formed by the second straight portion and the curved portion. A fourth embodiment intended for use with a stiff guidewire in a right coronary artery that is angularly displaced from its normal position and has an anterior take-off, comprises a first straight portion and a distal end portion formed by a second straight portion extending from the first straight portion at an angle in a first plane which is between 50.degree. and 70.degree. and at an angle in a second plane which is perpendicular to the first plane which is between 20.degree. and 40.degree.; a third straight tip portion extends from the second straight portion at an angle which is between 20.degree. and 30.degree. in the first plane and at an angle between 40.degree. and 50.degree. to the second straight portion. A fifth embodiment, intended for use with a stiff guidewire in a venous by-pass connecting the aorta to the distal segment of the right coronary artery, comprises a first straight shaft portion and a distal end portion consisting of a first curved portion extending the first straight portion, a second curved portion extending the first curved portion oppositely thereto and followed by a straight tip portion parallel to the first straight portion.
Still other preshaped catheters are available on the market such as, for instance, the catheter referred to as the "left Amplatz" or the "right Amplatz" which is constructed on variations of a basic shape having a straight elongated shaft followed by a first curve in a first direction followed by a second curve in the opposite direction, or the catheter referred to as the "Multipurpose" which bases on a shape having a substantially straight shaft portion followed by a curve, most of which have a flexibility which is unmodulated along their length.
A percutaneous transradial approach to catheterization is now being investigated because of favorable anatomical relations of the radial artery to its surrounding structures and the double blood supply to the hand. Potential benefits of this approach are safe transarterial coronary interventions combining rapid mobilization of the patient after intervention, with the resulting reduced hospitalization, and easy, safe, and effective hemostasis leading to a marked reduced incidence of access-site related major complications.
So far, there are, however, no specific catheters available for this technique. Typically, catheters such as those referred to hereinabove, which are specific to percutaneous transfemoral catheterization approach, have been used, however with relative lack of success on backup and coaxiality in alignment with the artery. Furthermore, they usually require a straightening wire for bringing the tip of the catheter in the direction of the ostium of the artery. And a plurality of catheters is needed to meet the various take-off configurations; and even so, they need some tricks to be properly used.
It is therefore an object of the present invention to improve the percutaneous transradial approach to catheterization by proposing a catheter specific to transradial catheterization. It is a further object of the invention to provide a catheter for transradial approach which avoids the drawbacks of the catheters for femoral approach used for transradial approach. Still a further object of the invention is to provide a catheter for transradial approach which is simple to manufacture with available techniques, and which avoids unnecessary costs as well as complex stock supply or ordering procedures.